Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
How Water Towers Work
You may have noticed a water tower rising up over your town, but you may not have given much thought to how it works. Practical Engineering has a nice video overview of this important piece of infrastructure, which municipalities use to store and pressurize water in public distribution systems. During off-peak hours, pumps fill the…
Water-Walking Geckos
Many animals can run on water. The tiniest creatures, like water striders, use surface tension to keep themselves atop the water. Larger creatures like the basilisk lizard or the grebe slap the water’s surface to generate a vertical impulse that keeps them aloft. Geckos, it turns out, can run on water, too, but they’re too…
Blackwater Rivers
Blackwater rivers, like the Suwannee River in Florida, carry waters so laden with organic material that they’re dyed a deep, dark brown. For the Suwannee, most of this material comes from the rich peat deposits of the Okefenokee Swamp that lies upstream. As vegetation in the swamp decays, tannins from the plants dissolve into the…
The Great Smog of London
Our atmosphere is active and ever-changing – except when it isn’t. Some areas, including many cities, are prone to what’s known as a temperature inversion, where a layer of cooler air gets trapped underneath a warmer one. Because this means that a dense layer is caught under a less dense one, the situation is stable…
Underwater Snakes, Gusty Flying, and Microswimmers
If you like your fluid dynamics with a healthy dose of biology, this video’s for you! Learn about the hydrodynamics of snake strikes, how birds fly in gusty crosswinds, and the mathematical underpinnings of a microswimmer’s journey. This is the final video in our FYFD/JFM collaboration featuring research from the 2017 APS DFD meeting. If…
Rattling Feathers for Attention
Peacocks are known for their colorful mating displays, but it turns out there’s more to them than meets the eye. To help them gain a penhen’s attention, peacocks will sometimes rattle their train-feathers. The sound this makes is mostly below the range of human hearing, but the rustle creates subtle vortices in the air that…
“Ice Formations”
As perfect as ice can appear, it always starts with a defect. Without a speck of dust or soot to act as a seed, supercooled water simply will not freeze. But these imperfections can lead to beauty. In “Ice Formations,” photographer Ryota Kajita captures some of the oddities of ice in Alaska’s interior swamps and ponds.…
The Clever Cat’s Tongue
Cats spend almost a quarter of their waking hours grooming, and their tongues are wonderfully specialized for this task, allowing them to clean, cool, and untangle themselves with ease. Anyone who’s ever been licked by a cat knows their tongues feel sandpaper-y. This is due to rear-facing hook-like structures called papillae that have a stiffness…
What Drives Droplets
There’s been a lot of interest recently in what goes on inside droplets made up of more than one fluid as they evaporate. This can be entertaining with liquids like whiskey or ouzo, but it has practical applications in ink-jet printing and manufacturing as well. And a new experiment suggests that we’ve been fundamentally wrong…
“If I Say”
The new Mumford & Sons single “If I Say” features a fluid-dynamical music video. It’s full of dendritic fingers and flowing colors – likely from combinations of inks, paints, and other fluids. Although the fingers are reminiscent of the viscosity-dependent Saffman-Taylor instability, these appear to be driven by variations in surface tension between the different fluids.…